From b71c8ec90ac5328ce437cf91ef2b4886ca25f9ba Mon Sep 17 00:00:00 2001
From: Han-Wen Nienhuys <hanwen@xs4all.nl>
Date: Wed, 10 Sep 2008 00:11:02 -0300
Subject: [PATCH] Revise GC asserts.

* libguile/gc.c (scm_i_gc): Change assert into printed warning.

* libguile/private-gc.h (nil): introduce scm_i_last_marked_cell_count,
  as a private mechanism for maintaining cell counts.  Remove variable
  scm_cells_allocated.
---
 libguile/gc.c         | 20 ++++++++++++++------
 libguile/gc.h         |  1 -
 libguile/private-gc.h |  5 +++--
 3 files changed, 17 insertions(+), 9 deletions(-)

diff --git a/libguile/gc.c b/libguile/gc.c
index f3ef585a9..a970eef0b 100644
--- a/libguile/gc.c
+++ b/libguile/gc.c
@@ -416,7 +416,7 @@ gc_end_stats ()
 
   scm_gc_cells_allocated_acc +=
     (double) scm_i_gc_sweep_stats.collected;
-  scm_gc_cells_marked_acc += (double) scm_cells_allocated;
+  scm_gc_cells_marked_acc += (double) scm_i_last_marked_cell_count;
   scm_gc_cells_marked_conservatively_acc += (double) scm_i_find_heap_calls;
   scm_gc_cells_swept_acc += (double) scm_i_gc_sweep_stats.swept;
 
@@ -558,6 +558,8 @@ scm_check_deprecated_memory_return ()
   scm_i_deprecated_memory_return = 0;
 }
 
+long int scm_i_last_marked_cell_count;
+
 /* Must be called while holding scm_i_sweep_mutex.
 
    This function is fairly long, but it touches various global
@@ -598,16 +600,22 @@ scm_i_gc (const char *what)
   scm_i_sweep_all_segments ("GC", &scm_i_gc_sweep_stats);
   scm_check_deprecated_memory_return ();
 
-#if (SCM_DEBUG_CELL_ACCESSES == 0 && SCM_SIZEOF_UNSIGNED_LONG ==4)
+#if (SCM_DEBUG_CELL_ACCESSES == 0 && SCM_SIZEOF_UNSIGNED_LONG == 4)
   /* Sanity check our numbers. */
   /* TODO(hanwen): figure out why the stats are off on x64_64. */
   /* If this was not true, someone touched mark bits outside of the
      mark phase. */
-  assert (scm_cells_allocated == scm_i_marked_count ());
+  if (scm_i_last_marked_cell_count != scm_i_marked_count ())
+    {
+      static char msg[] =
+	"The number of marked objects changed since the last GC: %d vs %d.";
+      /* At some point, we should probably use a deprecation warning. */
+      fprintf(stderr, msg, scm_i_last_marked_cell_count, scm_i_marked_count ());
+    }
   assert (scm_i_gc_sweep_stats.swept
 	  == (scm_i_master_freelist.heap_total_cells
 	      + scm_i_master_freelist2.heap_total_cells));
-  assert (scm_i_gc_sweep_stats.collected + scm_cells_allocated
+  assert (scm_i_gc_sweep_stats.collected + scm_i_last_marked_cell_count
 	  == scm_i_gc_sweep_stats.swept);
 #endif /* SCM_DEBUG_CELL_ACCESSES */
   
@@ -617,8 +625,8 @@ scm_i_gc (const char *what)
   scm_mark_all ();
   scm_gc_mark_time_taken += (scm_c_get_internal_run_time () - t_before_gc);
 
-  scm_cells_allocated = scm_i_marked_count ();
- 
+  scm_i_last_marked_cell_count = scm_cells_allocated = scm_i_marked_count ();
+
   /* Sweep
 
     TODO: the after_sweep hook should probably be moved to just before
diff --git a/libguile/gc.h b/libguile/gc.h
index fbd971036..58ac77241 100644
--- a/libguile/gc.h
+++ b/libguile/gc.h
@@ -287,7 +287,6 @@ SCM_API struct scm_t_cell_type_statistics scm_i_master_freelist;
 SCM_API struct scm_t_cell_type_statistics scm_i_master_freelist2;
 
 SCM_API unsigned long scm_gc_malloc_collected;
-SCM_API unsigned long scm_cells_allocated;
 SCM_API int scm_gc_malloc_yield_percentage;
 SCM_API unsigned long scm_mallocated;
 SCM_API unsigned long scm_mtrigger;
diff --git a/libguile/private-gc.h b/libguile/private-gc.h
index 93503ceb1..f5331ab1e 100644
--- a/libguile/private-gc.h
+++ b/libguile/private-gc.h
@@ -273,8 +273,9 @@ SCM_INTERNAL void scm_i_sweep_all_segments (char const *reason,
 SCM_INTERNAL SCM scm_i_all_segments_statistics (SCM hashtab);
 SCM_INTERNAL unsigned long *scm_i_segment_table_info(int *size);
 
-extern long int scm_i_deprecated_memory_return;
-extern long int scm_i_find_heap_calls;
+SCM_INTERNAL long int scm_i_deprecated_memory_return;
+SCM_INTERNAL long int scm_i_find_heap_calls;
+SCM_INTERNAL long int scm_i_last_marked_cell_count;
 
 /*
   global init funcs.
-- 
2.20.1